Links

Classifications

H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission

H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain

H04B1/0028—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage

H04B1/0032—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at baseband stage with analogue quadrature frequency conversion to and from the baseband

H—ELECTRICITY

H03—BASIC ELECTRONIC CIRCUITRY

H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER

H03D1/00—Demodulation of amplitude-modulated oscillations

H03D1/22—Homodyne or synchrodyne circuits

H03D1/2245—Homodyne or synchrodyne circuits using two quadrature channels

H—ELECTRICITY

H03—BASIC ELECTRONIC CIRCUITRY

H03F—AMPLIFIERS

H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements

H03F3/45—Differential amplifiers

H03F3/45071—Differential amplifiers with semiconductor devices only

H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier

H03F3/45475—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using IC blocks as the active amplifying circuit

H—ELECTRICITY

H03—BASIC ELECTRONIC CIRCUITRY

H03F—AMPLIFIERS

H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements

H03F3/50—Amplifiers in which input is applied to, or output is derived from, an impedance common to input and output circuits of the amplifying element, e.g. cathode follower

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04B—TRANSMISSION

H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission

H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain

H—ELECTRICITY

H04—ELECTRIC COMMUNICATION TECHNIQUE

H04B—TRANSMISSION

H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission

Abstract

A receiving circuit for digital demodulation communication system including channels, which reduces the power consumption of the receiving system, has a simple structure and consumes a small power. Two frequencies higher and lower the middle value of the frequencies of the channels are supplied to first and second frequency converting circuit (2 and 3) respectively from a local frequencyt signal generating circuit (4). Two output signals are generated for each of three signals of desired wave, higher channel, and lower channel. The desired wave commonly existing in the circuits (2 and 3) are extracted by means of a common wave extracting circuit (5). The frequency offset φo in the output of the circuit (5) is removed by means of a frequency offset circuit (6) and the unnecessary frequency components are removed through a filter (8). By using a commons wave extracting circuit (5) having a transformer to utilize the mutual inductance, the difference between the common and noncommon waves is twice larger than that of conventional.